Composite plastic parts are of great value in industry because of their high strength and light weight. Tubular, simple, and complex structures are produced by laying on, wrapping, or coating a core mold, or mandrel, with the composite plastic and curing the composite at appropriately high temperature.
Multiple problems arise, however, in creating a core mold of sufficient strength, appropriate surface characteristics, compatibility with the composite and the curing process, and ease of removing the core from the cured composite structure without damage to the composite or significant additional cost.
Core molds, or mandrels, have been made with sand and binders, plaster, plaster mixed with various binders, fillers such as cenospheres or graphite, and other materials.
It is sometimes advantageous to apply a coating or sealer on the mandrel prior to laying on, coating, or wrapping the mandrel with the raw composite material. However, there are problems with currently used coatings, including their becoming brittle and/or difficult to remove completely from the cured product.